Power

Battery Runtime Calculator

Estimate how long a battery can power a device off-grid.

Battery capacity, WhDevice power, WInverter efficiency, %Battery usable capacity, %

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Guides and explainers that help the calculator output make more sense.

A practical guide to estimating real battery runtime for camping and off-grid travel.

How to think through battery size, charging options and realistic camp loads.

Why usable capacity is a better planning number than advertised battery size.

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FAQ

Quick answers that help set expectations before you use or save this tool.

What does usable battery capacity mean?

Usable capacity reflects how much of your battery you actually plan to use, which is especially important for battery health and chemistry limits.

Why include inverter efficiency?

An inverter introduces losses, so a 1000 Wh battery does not deliver a full 1000 Wh to AC-powered devices.

Is this calculator good for van life and camping?

Yes. It is useful for overlanding, camper vans, power stations and backup battery planning.